Built-in pipes (date, currency, uppercase) in Angular - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the date pipe in Angular?

The date pipe formats a date value according to a specified format, making it easy to display dates in a readable way.

beginner

How does the currency pipe help in Angular templates?

The currency pipe formats a number as a currency string, adding currency symbols and decimal places based on locale and options.

beginner

What does the uppercase pipe do in Angular?

The uppercase pipe transforms all letters in a string to uppercase, useful for consistent text display.

intermediate

Show an example of using the date pipe to display the current date in 'fullDate' format.

Example: {{ today | date:'fullDate' }} where today is a Date object. This displays a full readable date like 'Tuesday, June 6, 2023'.

intermediate

Can you combine multiple pipes in Angular? For example, how to uppercase a currency formatted number?

Yes, you can chain pipes. Example: {{ amount | currency:'USD' | uppercase }} will format the number as USD currency and then convert the result to uppercase letters.

Which Angular pipe would you use to format a number as money?

A json

B date

C uppercase

D currency

The currency pipe formats numbers as currency values.

What does the uppercase pipe do?

A Converts text to uppercase

B Formats dates

C Converts text to lowercase

D Formats numbers

The uppercase pipe changes all letters in a string to uppercase.

How do you apply a pipe in an Angular template?

A Using square brackets []

B Using the pipe symbol |

C Using parentheses ()

D Using curly braces {}

Pipes are applied using the pipe symbol | in Angular templates.

Which pipe would you use to display a date as 'Jun 6, 2023'?

A uppercase

B currency

C date:'mediumDate'

D json

The date pipe with the format 'mediumDate' shows dates like 'Jun 6, 2023'.

Can you chain pipes in Angular templates?

A Yes, by using multiple pipe symbols |

B No, only one pipe per expression

C Yes, by separating with commas

D Only with custom pipes

You can chain pipes by using multiple | symbols, like {{ value | pipe1 | pipe2 }}.

Explain how to use the Angular date pipe to format a date and why it is helpful.

Think about how dates look different in various places and how the pipe helps.

Describe how you can combine the currency and uppercase pipes in Angular and what the result looks like.

Consider how pipes process data step-by-step.

Practice

1. What does the Angular uppercase pipe do when applied to a string in a template?

easy

A. Reverses the string characters.

B. Converts all letters in the string to lowercase.

C. Capitalizes only the first letter of the string.

D. Converts all letters in the string to uppercase.

Solution

1. Step 1: Understand the purpose of the uppercase pipe

   The uppercase pipe is designed to transform text to all capital letters in Angular templates.

2. Step 2: Compare with other text transformations

   Unlike lowercase or capitalize, uppercase changes every letter to uppercase.

3. Final Answer:

   Converts all letters in the string to uppercase. -> Option D

4. Quick Check:

   uppercase pipe = all caps [OK]

Hint: Uppercase pipe makes all letters capital [OK]

Common Mistakes:

• Confusing uppercase with lowercase pipe
• Thinking it only capitalizes first letter
• Assuming it reverses the string

2. Which of the following is the correct syntax to format a date using Angular's date pipe to show only the year in a template?

easy

A. {{ myDate | date:'yyyy' }}

B. {{ myDate | date:'YYYY' }}

C. {{ myDate | date:'year' }}

D. {{ myDate | date:'yy' }}

Solution

1. Step 1: Recall Angular date pipe format codes

   Angular uses lowercase 'yyyy' to represent the full year in date pipe formatting.

2. Step 2: Check each option's format string

   {{ myDate | date:'yyyy' }} uses 'yyyy' correctly; A uses uppercase which is invalid; C uses 'year' which is not a valid format; D uses 'yy' which shows two-digit year.

3. Final Answer:

   {{ myDate | date:'yyyy' }} -> Option A

4. Quick Check:

   Year format = 'yyyy' [OK]

Hint: Use lowercase 'yyyy' for full year in date pipe [OK]

Common Mistakes:

• Using uppercase 'YYYY' instead of 'yyyy'
• Using descriptive words like 'year' instead of format codes
• Using 'yy' which shows only two digits

3. Given the Angular template code:

{{ 1234.5 | currency:'USD':'symbol':'1.2-2' }}

What will be the rendered output?

medium

A. $1,234.50

B. $1234.5

C. USD 1234.50

D. $1,234.5

Solution

1. Step 1: Understand the currency pipe parameters

   The currency pipe format is: currency code 'USD', display as symbol '$', and digit info '1.2-2' means minimum 1 digit before decimal, minimum 2 decimals, maximum 2 decimals.

2. Step 2: Apply formatting to the number 1234.5

   Number 1234.5 is formatted with commas and two decimals: $1,234.50.

3. Final Answer:

   $1,234.50 -> Option A

4. Quick Check:

   Currency pipe with '1.2-2' = two decimals [OK]

Hint: Currency pipe '1.2-2' means two decimals [OK]

Common Mistakes:

• Ignoring decimal places and showing one decimal
• Using currency code instead of symbol
• Not adding thousand separators

4. Identify the error in this Angular template code:

{{ today | date:'MM-DD-YYYY' }}

medium

A. The date pipe cannot format month and day.

B. The pipe name 'date' is misspelled.

C. The date format string uses uppercase 'YYYY' which is invalid.

D. The variable 'today' is not defined.

Solution

1. Step 1: Check the date format string correctness

   Angular date pipe requires lowercase 'yyyy' for year, not uppercase 'YYYY'.

2. Step 2: Verify other parts of the code

   The pipe name 'date' is correct, 'today' is assumed defined, and date pipe can format month and day.

3. Final Answer:

   The date format string uses uppercase 'YYYY' which is invalid. -> Option C

4. Quick Check:

   Date pipe year format = 'yyyy' lowercase [OK]

Hint: Use lowercase 'yyyy' in date pipe format strings [OK]

Common Mistakes:

• Using uppercase 'YYYY' instead of 'yyyy'
• Assuming pipe name is wrong
• Ignoring variable definition issues

5. You want to display a product price in Euros with the currency symbol and exactly 3 decimal places in Angular. Which pipe usage is correct?

hard

A. {{ price | currency:'EUR':'code':'1.2-2' }}

B. {{ price | currency:'EUR':'symbol':'1.3-3' }}

C. {{ price | currency:'EUR':'symbol':'1.0-2' }}

D. {{ price | currency:'USD':'symbol':'1.3-3' }}

Solution

1. Step 1: Identify the currency code and symbol usage

   To show Euros with symbol €, use currency code 'EUR' and display 'symbol'.

2. Step 2: Set decimal places to exactly 3

   The digit info '1.3-3' means minimum 1 digit before decimal, exactly 3 decimals.

3. Step 3: Check other options for correctness

   {{ price | currency:'EUR':'code':'1.2-2' }} uses 'code' display and 2 decimals; C uses 2 decimals; D uses USD instead of EUR.

4. Final Answer:

   {{ price | currency:'EUR':'symbol':'1.3-3' }} -> Option B

5. Quick Check:

   Currency EUR with 3 decimals = {{ price | currency:'EUR':'symbol':'1.3-3' }} [OK]

Hint: Use '1.3-3' for exactly 3 decimals in currency pipe [OK]

Common Mistakes:

• Using wrong currency code or symbol
• Setting wrong decimal places
• Mixing currency codes (USD instead of EUR)